f15dd06473
This avoids concurrent access errors. This is especially important when using Unsafe-based LongArrays, since we have concurrent access to the underlying memory-mapped file. If pull the rug from under the caller by closing the file, we'll get a SIGSEGV. Even with a "safe" MemorySegment, we'll get ugly stacktraces if we close the file while a thread is still accessing it. So we spin up a thread that sleeps for a minute before actually unmapping the file, allowing any ongoing requests to wrap up. This is 100% a hack, but it lets us get away with doing this without adding locks to the index readers. Since this is "just" mmapped data, and this operation happens optimistically once a month, it should be safe if the call gets lost. |
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| .. | ||
| api | ||
| common | ||
| features-convert | ||
| features-crawl | ||
| features-index | ||
| features-qs | ||
| features-search | ||
| libraries | ||
| process-models | ||
| processes | ||
| services-application | ||
| services-core | ||
| tools | ||
| readme.md | ||
Code
This is a pretty large and diverse project with many moving parts.
You'll find a short description in each module of what it does and how it relates to other modules. The modules each have names like "library" or "process" or "feature". These have specific meanings. See doc/module-taxonomy.md.
Overview
A map of the most important components and how they relate can be found below.
The core part of the search engine is the index service, which is responsible for storing and retrieving the document data. The index serive is partitioned, along with the executor service, which is responsible for executing processes. At least one instance of each service must be run, but more can be run alongside. Multiple partitions is desirable in production to distribute load across multiple physical drives, as well as reducing the impact of downtime.
Search queries are delegated via the query service, which is a proxy that fans out the query to all eligible index services. The control service is responsible for distributing commands to the executor service, and for monitoring the health of the system. It also offers a web interface for operating the system.
Services
- core services Most of these services are stateful, memory hungry, and doing heavy lifting.
- application services Mostly stateless gateways providing access to the core services.
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- api - public API
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- search - marginalia search application
- an internal API
Processes
Processes are batch jobs that deal with data retrieval, processing and loading. These are spawned and orchestrated by the executor service, which is controlled by the control service.
Tools
Features
Features are relatively stand-alone components that serve some part of the domain. They aren't domain-independent, but isolated.
Libraries and primitives
Libraries are stand-alone code that is independent of the domain logic.